SOLUTION: I need help to understand how to solve this: sqrt of x+20-x=0

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Question 537469: I need help to understand how to solve this:
sqrt of x+20-x=0
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
solve this:
sqrt of x+20-x=0
Assume the problem is:
sqrt%28x%2B20%29-+x+=+0
Add x to both sides
sqrt%28x%2B20%29+=+x
Square both sides
x + 20 = x^2
Arrange as a quadratic equation
0 = x^2 - x - 20
Factors to
(x-5)(x+4) = 0
Two solutions
x = 5
and
x = -4
:
Check both solutions in the original equation